When the foul stench emanating from one's gob is so potent, that it will actually cause an immediate involuntary gag reflex, burn your eyes, and make you want to pack your sinus cavity with rotting skunk carcasses just to mask the smell.

As soon as I opened the door to the lab, Fred's shit breath hit me in the face like a sac of hammers, even though he was about 80 feet away. That, my friends, is potent shit breath.

When someones breath smells so bad, it's like hot, burning garbage. When you can't stand to talk to, sit next to, or even be around someone because their breath smells like a big dog just took a dump in their mouth.